Would be good to add oAuth2 for SMTP on SaaS. As far as I understand currently we can use only basic authentication mail server on SaaS. In many environments IT authorities would prefer to do not leave this exposed.
Microsoft has declared that Basic Authentication will stop working for Exchange Online in 2022.
https://techcommunity.microsoft.com/t5/exchange-team-blog/basic-authentication-and-exchange-online-s...
